+1 for porro prism design, but a few words of caution:
- be VERY careful if buying marine or otherwise weatherproof and don't buy into "autofocus" crap, more truthful would be "individual focus"
It's easiest to weatherproof porro prism by not having center focus. This is referred to autofocus because it's not practical to keep focusing the individual eye pieces to different distances, and thus your eyes must do all the work. This will strain your eyes very fast if glassing in a stalking fashion.
- try to get center focus for easy viewing
- try to get nitrogen fill for ease of mind
- if using for low light, try to find a model with newish coatings
Problem is, big name brands are not making porro prism anymore, they've concluded that customers want roof prism designs. Older models don't have very good coatings on lenses. Fortunately, there's some smaller companies offering products in this category.
I just bought a pair of Delta Optical 7x50 Titanium binos to try for extremely low light use (night time ambush). I wanted cheaper, smaller, lighter binos to complement my 8x56 Docters. Other "musts" were porro prism design, central focus and nitrogen fill. To my understanding Delta is a Polish company that orders Chinese optics to their own specifications and sells them. I based my research mostly on allbinos.com, since I have good experience with their reviews.
While the Deltas are lacking in ergonomics department (like being completely unusable with specs, luckily I don't use specs; you can modify them though) I haven't been able to find any difference in pure low light performance to my top of the line Docters (which you find are also porro prism design, and on purpose!).
Delta Optical Titanium 7x50 - binoculars review - allbinos.com
Docter Nobilem 8x56 B/GA - binoculars review - allbinos.com